EP1805540A1 - Optical sensor fiber with protective jacketing layers - Google Patents

Optical sensor fiber with protective jacketing layers

Info

Publication number
EP1805540A1
EP1805540A1 EP05813750A EP05813750A EP1805540A1 EP 1805540 A1 EP1805540 A1 EP 1805540A1 EP 05813750 A EP05813750 A EP 05813750A EP 05813750 A EP05813750 A EP 05813750A EP 1805540 A1 EP1805540 A1 EP 1805540A1
Authority
EP
European Patent Office
Prior art keywords
layer
optical fiber
jacketing
cladding
core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05813750A
Other languages
German (de)
French (fr)
Other versions
EP1805540A4 (en
Inventor
Sanan Shaibani
Joseph Krysthowiak
John Mansell
Akbar Arab Sadenghabadi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northrop Grumman Guidance and Electronics Co Inc
Original Assignee
Northrop Grumman Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northrop Grumman Corp filed Critical Northrop Grumman Corp
Publication of EP1805540A1 publication Critical patent/EP1805540A1/en
Publication of EP1805540A4 publication Critical patent/EP1805540A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/16—Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
    • G01V1/18—Receiving elements, e.g. seismometer, geophone or torque detectors, for localised single point measurements
    • G01V1/186—Hydrophones
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings

Definitions

  • optical fibers especially optical fibers that comprise a core layer, a cladding layer over the core layer, and a coating layer over the cladding layer, a protective layer over the coating layer, and sensory arrays that include such optical fibers.
  • an optical fiber sensor array comprising one or more Fiber Bragg Gratings (FBG's), written in the core or cladding of the fibers, is over coated with a protective material, e.g., a thin plastic, specifically selected for the intended environment of the array.
  • the protective over coating is preferably of sufficient thickness to minimize micro bending of such arrays.
  • Some of these arrays may include fibers having lengths in the range of a few meters up to several kilometers. These arrays may be exposed to severe environmental conditions including extremes of heat and cold and corrosive chemicals, and must therefore be robust, and resistant to deterioration under such conditions.
  • Optical fibers are used extensively in sensor arrays, in part because of the ease in forming the arrays. These fibers may have a core layer, e.g., core layer made of glass, an outer cladding layer, e.g., a layer made of glass over the core, and a protective buffer coating layer over the cladding.
  • core layer e.g., core layer made of glass
  • outer cladding layer e.g., a layer made of glass over the core
  • a protective buffer coating layer over the cladding.
  • protective layers do not necessarily protect sensor arrays including-.them, however.
  • optical fiber pressure sensor arrays that include such optical fibers on a wrapped mandrel may have entry and exit points exposed to potential damage. Such fibers and arrays need better protection.
  • Fiber Bragg Gratings FBG's
  • US Patent No. 5,620,495 discloses writing FBG's in polymer-coated optical -fibers without removing the polymer coating.
  • FBG's may be written in the fibers by removing the buffer or coating layer over a short distance, e.g., a few millimeters, to form a gap, then forming Bragg gratings in the gap. The gap is then closed with a patch.
  • US Patent No. 4,725,110 disclosing methods for forming FBG's within fiber optics.
  • Such methods may degrade the protective buffer of the fiber and may not provide adequate protection in the actual operating environment, either because the coating has been formulated for transparency, or has been stripped and recoated.
  • This invention protects fiber sensor arrays with many FBG's in arrays such as those disclosed in US Patent No. 5,987,197 and up-coats each continuous fiber array length with a protective layer.
  • Optical fibers that include Fiber Bragg Gratings (FBG's), written in the core or cladding of the fibers, further comprise a core layer, a cladding layer over the core layer, a eoating layer over the cladding layer, and an outer jacketing layer over the buffer or coating layer.
  • This outer jacketing layer may be uniform in thickness, and may be, for example, from about 1 to about 900 microns in thickness.
  • the jacketing material may be
  • thermoset made of materials such as a thermoset, a polyamide, or a thermoplastic, e.g., Hytrel®, a
  • thermoplastics and thermosets are examples of suitable materials.
  • thermosets are examples of thermoplastics and thermosets:
  • the optical fibers are made, and the Fiber Bragg Gratings (FBG's) formed, before the jacketing material is applied.
  • the jacketing or over coat covers the fiber over its entire length, protecting both fiber and FBG's.
  • the over coat is uniform in thickness, homogeneous in composition and, after application, solid and substantially free of defects such as bubbles, voids, thin regions, and breaks.
  • the optical fibers may comprise a core layer comprising materials such as glass, a cladding layer over the core layer, where the cladding layer may comprise glass, and a coating layer over the cladding layer.
  • the coating layer may be made of polymer.
  • the core, cladding layer and buffer layer are of substantially uniform thickness.
  • the diameter of the core may be about 1 to about 20 microns.
  • the thickness of the cladding layer may be in the range of about 10 to about 200 microns.
  • the thickness of the buffer layer may be in the range of about 20 to about 400 microns.
  • the protective outer layer thickness may be in the range of about 1 to 900 microns.
  • Such optical fibers may form part of a sensor array, such as a pressure sensor array.
  • These arrays include a mandrel with optical fiber wrapped around the mandrel.
  • the optical fibers/mandrel assembly may also be coated with an epoxy.
  • a hollow tube made of a substance suitable for forming the outer protective layer may be heated "to the softening point, and then drawn over the outer layer, e.g., buffer layer of the optical fiber. Upon cooling, the outer jacketing layer shrinks to fit over and adhere to the buffer layer.
  • a buffer layer may be drawn onto the fiber.
  • Such a buffer coating may be applied as a liquid. Once applied, the coating cools and solidifies over the length of the fiber, encapsulating an entire sensor array. The actual kinds and methods of over coating the sensor may depend on the operating environment for the array, or on the process in which the array is expected to operate.
  • FIG. 1 shows an optical fiber wrapped around a mandrel
  • FIG. 2 shows a cross-section of an optical fiber that includes the protective outer jacket applied atop the buffer layer and atop the core and cladding of ari optical fiber.
  • FIG. 1 shows optical fiber 1 wrapped around the length of hydrophone mandrel 2.
  • the entire mandrel may be coated with epoxy.
  • FIG. 2 shows optical fiber 10 in cross-section.
  • Optical fiber 10 includes glass core 1 1, cladding 12, buffer layer 13, protective layer 14, and FBG's 15.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Geology (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Optics & Photonics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Surface Treatment Of Glass Fibres Or Filaments (AREA)
  • Optical Transform (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

Optical fibers, especially those having a core layer, a cladding layer over the core layer, FBG´s formed in the core layer, the cladding layer, or both, a buffer layer over the cladding layer, and an outer jacketing layer.

Description

OPTICAL SENSOR FIBER WITH PROTECTIVE JACKETING LAYERS
FIELD OF THE INVENTION
The field of this invention is optical fibers, especially optical fibers that comprise a core layer, a cladding layer over the core layer, and a coating layer over the cladding layer, a protective layer over the coating layer, and sensory arrays that include such optical fibers. More particularly, an optical fiber sensor array comprising one or more Fiber Bragg Gratings (FBG's), written in the core or cladding of the fibers, is over coated with a protective material, e.g., a thin plastic, specifically selected for the intended environment of the array. The protective over coating is preferably of sufficient thickness to minimize micro bending of such arrays.
Some of these arrays, e.g., geophysical arrays, interferometers and hydrophones, may include fibers having lengths in the range of a few meters up to several kilometers. These arrays may be exposed to severe environmental conditions including extremes of heat and cold and corrosive chemicals, and must therefore be robust, and resistant to deterioration under such conditions.
BACKGROUND OF THE INVENTION
Optical fibers are used extensively in sensor arrays, in part because of the ease in forming the arrays. These fibers may have a core layer, e.g., core layer made of glass, an outer cladding layer, e.g., a layer made of glass over the core, and a protective buffer coating layer over the cladding. Unfortunately, these fibers and arrays have disadvantages. Often these sensors and arrays lack adequate protection when exposed to adverse environmental conditions. Others have disclosed placing a protective coating or buffer layer on such fibers. See US Patent No. 6,563,996, disclosing optical fibers having a protective primary coating composition including a monomer with a pendant hydroxyl function group. Such
protective layers do not necessarily protect sensor arrays including-.them, however. For
example, optical fiber pressure sensor arrays that include such optical fibers on a wrapped mandrel may have entry and exit points exposed to potential damage. Such fibers and arrays need better protection.
These fiber arrays often include Fiber Bragg Gratings (FBG's) formed in the optical fibers through transparent buffer or coating layers, as by laser etching. US Patent No. 5,620,495 discloses writing FBG's in polymer-coated optical -fibers without removing the polymer coating. Alternatively, FBG's may be written in the fibers by removing the buffer or coating layer over a short distance, e.g., a few millimeters, to form a gap, then forming Bragg gratings in the gap. The gap is then closed with a patch. See also US Patent No. 4,725,110 disclosing methods for forming FBG's within fiber optics.
Such methods may degrade the protective buffer of the fiber and may not provide adequate protection in the actual operating environment, either because the coating has been formulated for transparency, or has been stripped and recoated. This invention protects fiber sensor arrays with many FBG's in arrays such as those disclosed in US Patent No. 5,987,197 and up-coats each continuous fiber array length with a protective layer.
SUMMARY OF THE INVENTION
Optical fibers that include Fiber Bragg Gratings (FBG's), written in the core or cladding of the fibers, further comprise a core layer, a cladding layer over the core layer, a eoating layer over the cladding layer, and an outer jacketing layer over the buffer or coating layer. This outer jacketing layer may be uniform in thickness, and may be, for example, from about 1 to about 900 microns in thickness. The jacketing material may be
made of materials such as a thermoset, a polyamide, or a thermoplastic, e.g., Hytrel®, a
DuPont trademark.
Among other suitable materials are the following thermoplastics and thermosets:
THERMOPLASTICS
• Acrylonitrile butadiene styrene
• Cellulose acetate
• Cellulose acetate butyrate
• Chlorinated trifluoroethylene
• Polyacetal
• Polyamide (nylon)
• Polybutylene terephthalate
• Polycarbonate
• Polyethylene
• Polyester
• Polyimide
• Polymethylmethacrylate
• Polypropylene
• Polystyrene
• Polysulfone
• Polytetrafluoroethylene
• Polyvinyl chloride
THERMOSETS
• Diallyl phthalate
• EPOXY
• Melamine formaldehyde
• Phenol formaldehyde .
• Polyester
• Urea formaldehyde
Preferably, the optical fibers are made, and the Fiber Bragg Gratings (FBG's) formed, before the jacketing material is applied. The jacketing or over coat covers the fiber over its entire length, protecting both fiber and FBG's. Preferably, the over coat is uniform in thickness, homogeneous in composition and, after application, solid and substantially free of defects such as bubbles, voids, thin regions, and breaks.
The optical fibers may comprise a core layer comprising materials such as glass, a cladding layer over the core layer, where the cladding layer may comprise glass, and a coating layer over the cladding layer. The coating layer may be made of polymer. The core, cladding layer and buffer layer are of substantially uniform thickness. The diameter of the core may be about 1 to about 20 microns. The thickness of the cladding layer may be in the range of about 10 to about 200 microns. The thickness of the buffer layer may be in the range of about 20 to about 400 microns. The protective outer layer thickness may be in the range of about 1 to 900 microns.
Such optical fibers may form part of a sensor array, such as a pressure sensor array. These arrays include a mandrel with optical fiber wrapped around the mandrel. The optical fibers/mandrel assembly may also be coated with an epoxy.
To apply the outer protective layer, a hollow tube made of a substance suitable for forming the outer protective layer may be heated "to the softening point, and then drawn over the outer layer, e.g., buffer layer of the optical fiber. Upon cooling, the outer jacketing layer shrinks to fit over and adhere to the buffer layer. Alternatively, a buffer layer may be drawn onto the fiber. Such a buffer coating may be applied as a liquid. Once applied, the coating cools and solidifies over the length of the fiber, encapsulating an entire sensor array. The actual kinds and methods of over coating the sensor may depend on the operating environment for the array, or on the process in which the array is expected to operate. BRIEF DESCRIPTION OF THE DRAWINGS
The jacketed optical fibers of this invention and the assemblies including them can better be understood by reference to the drawings in which:
FIG. 1 shows an optical fiber wrapped around a mandrel; and
FIG. 2 shows a cross-section of an optical fiber that includes the protective outer jacket applied atop the buffer layer and atop the core and cladding of ari optical fiber.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows optical fiber 1 wrapped around the length of hydrophone mandrel 2. The entire mandrel may be coated with epoxy.
FIG. 2 shows optical fiber 10 in cross-section. Optical fiber 10 includes glass core 1 1, cladding 12, buffer layer 13, protective layer 14, and FBG's 15.

Claims

1. An optical fiber comprises a core layer, a cladding layer over the core layer, a buffer layer over the cladding layer, an outer jacketing layer over the buffer layer, and one or more FBG's formed in the core layer, cladding layer, or both, said jacketing layer having a composition and thickness adapted to the intended use environment for said optical fiber.
2. The optical fiber of claim 1 wherein said core layer is made of glass, said cladding layer is made of glass, and said jacketing layer is made of Hytrel®-curab\e coating.
3. The optical fiber of claim 1 wherein said core layer has a thickness in the range of about 1 to about 20 microns, said cladding layer has a thickness in the range of about 10 to about 200 microns, said buffer layer has a thickness in the range of about 20 to about 400 microns, and said outer jacketing layer has a thickness in the range of about 1 to about 900 microns.
4. The optical fiber of claim 1 wherein said core layer is made of glass and has a thickness in the range of about 1 to about 20 microns, said cladding layer is made of glass and has a thickness in the range of about 10 to about 200 microns, said buffer layer comprises of polymer and has a thickness in the range of about 20 to about 400 microns, and said outer jacketing layer is made of Hytrel® and has a range of about 1 to about 900 microns.
5. A sensor array comprising the optical fiber of claim 1.
6. A sensor array comprising the optical fiber of claim 2.
7. A sensor array comprising the optical fiber of claim 3.
8. A sensor array comprising the optical fiber of claim 4.
9. The method of making an optical fiber comprising forming an optical fiber that
includes a core layer, a cladding layer over the core layer, arbuffer layer over the cladding layer, and one or more FBG's formed in the core layer, cladding layer, or both, said jacketing layer having a composition and thickness adapted to the intended use environment for said optical fiber, comprising drawing over said buffer layer an outer jacketing layer in the form of heat-softened tubular jacketing material, then cooling said jacketing material to shrink said jacketing layer onto said buffer layer.
10. The method of making an optical fiber comprising forming an optical fiber that includes a core layer, a cladding layer over the core layer, a buffer layer over the cladding layer, and one or more FBG's formed in the core layer, cladding layer, or both, said jacketing layer having a composition and thickness adapted to the intended use environment for said optical fiber, comprising applying said buffer layer as a liquid, and allowing said buffer layer to solidify.
11. The method of making an optical fiber assembly comprising forming an optical fiber assembly that includes a core layer, a cladding layer over the core layer, a buffer layer over the cladding layer, and one or more FBG's formed in the core layer, cladding layer, or both, said jacketing layer having a composition and thickness adapted to the intended use environment for said optical fiber, comprising applying said jacketing layer as a liquid to said assembly, and allowing said jacketing layer to set.
EP05813750A 2004-10-14 2005-10-13 Optical sensor fiber with protective jacketing layers Withdrawn EP1805540A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10/966,751 US7327907B2 (en) 2004-10-14 2004-10-14 Optical sensor fiber with protective jacketing layers
PCT/US2005/036855 WO2006044558A1 (en) 2004-10-14 2005-10-13 Optical sensor fiber with protective jacketing layers

Publications (2)

Publication Number Publication Date
EP1805540A1 true EP1805540A1 (en) 2007-07-11
EP1805540A4 EP1805540A4 (en) 2008-01-02

Family

ID=36180835

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05813750A Withdrawn EP1805540A4 (en) 2004-10-14 2005-10-13 Optical sensor fiber with protective jacketing layers

Country Status (5)

Country Link
US (1) US7327907B2 (en)
EP (1) EP1805540A4 (en)
CA (1) CA2587518C (en)
NO (1) NO20072331L (en)
WO (1) WO2006044558A1 (en)

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US20110096624A1 (en) * 2009-10-26 2011-04-28 Harini Varadarajan Sensing Technique for Seismic Exploration
US9103736B2 (en) 2010-12-03 2015-08-11 Baker Hughes Incorporated Modeling an interpretation of real time compaction modeling data from multi-section monitoring system
US9557239B2 (en) 2010-12-03 2017-01-31 Baker Hughes Incorporated Determination of strain components for different deformation modes using a filter
US9194973B2 (en) 2010-12-03 2015-11-24 Baker Hughes Incorporated Self adaptive two dimensional filter for distributed sensing data
US8701500B2 (en) 2011-12-02 2014-04-22 Lake Shore Cryotronics, Inc. Method and apparatus for fixing strained optical fibers against creep and temperature and strain sensors using said technology
US9605534B2 (en) 2013-11-13 2017-03-28 Baker Hughes Incorporated Real-time flow injection monitoring using distributed Bragg grating
WO2015085423A1 (en) * 2013-12-13 2015-06-18 Hifi Engineering Inc. Apparatus for detecting acoustic signals in a housing
CA2940278C (en) 2014-02-19 2022-08-16 Sonoro, Llc Polymer coated optical fiber
CN109860455B (en) * 2018-12-17 2021-12-14 中汽数据有限公司 Power battery safety device

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WO2001049625A1 (en) 1999-12-30 2001-07-12 Corning Incorporated Optical fibers prepared with a primary coating composition including a monomer with a pendant hydroxyl functional group
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Also Published As

Publication number Publication date
CA2587518A1 (en) 2006-04-27
CA2587518C (en) 2012-07-10
WO2006044558A1 (en) 2006-04-27
EP1805540A4 (en) 2008-01-02
US20060083463A1 (en) 2006-04-20
NO20072331L (en) 2007-06-18
US7327907B2 (en) 2008-02-05

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